Carpet backing formulations are prone to growth/buckling issues due to high growth forces that arise when the material is subjected to high temperatures. In general, these forces are related to the stiffness of the material, up to the point where the material begins to melt/soften. Historically, highly flexible, PVC-based formulations have been used for carpet backing formulations. But more recently, product safety and sustainability concerns have arisen about the use of products containing chlorine and/or various plasticizers, such as phthalates. For filled, olefin-based polymer formulations, growth forces are particularly critical in backing applications. In highly crystalline polymers, significant growth forces exist, such that buckling is common problem. Polymers of lower crystallinity require stiffening materials, such as fillers, to improve their properties for backing applications. However, these stiffening materials also cause expansion and buckling in the final compositions. Thus, there is a need for new polymer compositions that have reduced growth forces, and which can be used in carpets, and in particular, in carpet backing formulations, without causing expansion and buckling problems.
U.S. Pat. No. 6,241,168 discloses “carpet scrap containing mixtures” of polyesters and/or polyamides and polyolefins, and which are compatibilized with ultralow density polyethylene (ULDPE) to make homogeneous thermoplastic blends.
European Patent EP 0719301B1 discloses a polymeric blend, formed from recycled carpet scrap and selected compatibilizing agents and/or a poly(ethylene-co-vinylacetate), and the products produced from such blend.
U.S. Pat. No. 6,814,826 discloses processed waste carpeting as a filler in the production of a hot melt carpet backcoating, roofing materials, or other similar products. Waste carpeting (post-consumer and/or waste from new carpet manufacture) is collected and size-reduced, typically in a first, coarse size-reduction, and then, after densification, to a finer size-reduction. The size-reduced, waste carpeting is added as filler to at least one other material, such as polymers in a standard latex, EVA, or PVC carpet backcoatings, to provide a hot melt composite used in the manufacture of a product (like carpet backcoating). The waste carpeting may provide between about 40-100% of the filler of a carpet backcoating, with any remainder made up by conventional fillers, such as calcium carbonate.
US Publication No. 2008/0113146 discloses carpet and methods of making and recycling carpet. In one aspect, the carpet includes the following: a primary backing, which has a face and a back surface; a plurality of fibers attached to the primary backing, and extending from the face of the primary backing, and exposed at the back surface of the primary backing; an adhesive composition backing; and an optional secondary backing adjacent to the adhesive backing. The method of making carpet includes extrusion coating the adhesive composition onto the back surface of a primary backing, to form the adhesive composition backing. The method of recycling carpet can recover one or more polymeric carpet components.
U.S. Publication No. 2008/0206583 discloses a composition that includes at least one compatibilizer having at least one polyolefin and at least one polar group. The composition can include a blend of polymers. Surface coverings and floor coverings, such as laminated floor coverings, formed from the composition, are also described.
U.S. Pat. No. 7357971 discloses carpet and methods of making carpet. In one aspect, the carpet includes (a) a primary backing, (b) a plurality of fibers attached to the primary backing, (c) an adhesive backing, (d) an optional secondary backing adjacent to the adhesive backing, and (e) at least one homogeneously branched ethylene polymer. The method includes extrusion coating at least one homogeneously branched ethylene polymer onto the back surface of a primary backing to provide an adhesive backing. The preferred homogeneously branched ethylene polymer is a substantially linear ethylene polymer. See also U.S. Pat. No. 7,338,698 and EP0963476B1.
International Publication No. WO 2010/012041 discloses a composition comprising a very low density polyethylene having a density of less than 0.905 g/cm3, an ethylene acrylic acid copolymer, a thermoplastic starch and/or the constituent components thereof.
U.S. Publication No. 2006/0094824 discloses polymer compositions having elastomeric features, such as an extended elastic domain. The polymer compositions comprise a polyolefin; an ethylene vinyl acetate copolymer, an ethylene methyl acrylate copolymer, or a combination of an ethylene vinyl acetate copolymer and an ethylene methyl acrylate copolymer; a metallocene catalyzed polyethylene; and, optionally, an ethylene acid copolymer.
U.S. Pat. No. 6,815,023 discloses a polymer blend, and mono-and multilayer films made therefrom. The blend preferably has a first copolymer of ethylene and hexene-1, and having a copolymer melting point of 80 to 98° C., preferably of 80 to 92° C.; a second copolymer of ethylene and at least one alpha-olefin, and having a copolymer melting point of 115 to 128° C.; and a third copolymer of ethylene and a vinyl ester or alkyl acrylate, and having a melting point of 60 to 110° C.
U.S. Pat. NO. 5,936,058 discloses a composition comprising: a) 2 to 50 weight % of a first ethylene alpha-olefin copolymer having a density of 0.86 to 0.91 g/cc, a melt index of 150 g/10 min or less, and an Mw/Mn of 4 or less, and modified with an unsaturated acid or anhydride, and a second ethylene alpha-olefin copolymer having a density of 0.86 to 0.925 g/cm3, and/or a homopolyethylene; and b) 98 to 50 weight percent of a thermoplastic polymer comprising a functional group capable of interacting with the unsaturated acid or anhydride.
U.S. Pat. No. 4,983,435 discloses an adhesive used between a polypropylene layer and an ethylene/vinyl alcohol copolymer layer. The adhesive composition comprises from 98.9 to 59.9%, by weight, of a modified polypropylene (A), partly or fully grafted with an unsaturated carboxylic acid or its derivative; from 1.0 to 40%, by weight, of an ethylene/alpha-olefin copolymer (B), having a density from 0.915 to 0.940 g/cc, and a melting point from 115 to 130° C.; and 0.1%, by weight, or more, but less than 3%, by weight, of a hydrocarbon type synthetic elastomer (C).
European Patent Application EP 0479457A1 discloses polyolefin containing compositions comprising A), a high density polyethylene grafted with an unsaturated carboxylic acid or derivative, and B) a very low density polyethylene, and preferably either consist essentially of A and B, or also comprises C) another polyolefin, such as HDPE or LDPE.
U.S. Pat. No. 4,487,885 discloses resin blends comprising (a) a graft copolymer of a polyethylene backbone grafted with at least one grafting monomer, comprising one or more polymerizable ethylenically unsaturated carboxylic acids or acid derivatives, such as acid anhydrides, acid esters, salts, amides, imides and the like, (b) a LDPE, a linear low density polyethylene, or an ethylene-unsaturated ester copolymer and (c) a poly(alpha-olefin).
U.S. Pat. No. 4,394,485 discloses compositions comprising blends of a graft copolymer of a polyethylene backbone grafted with at least one grafting monomer, comprising one or more of polymerizable ethylenically unsaturated carboxylic acids or the anhydrides of such acids. The grafted copolymer is blended with a blending resin that is a mixture of one or more high density polyethylenes, one or more linear low density polyethylenes, and one or more polypropylenes.
U.S. Pat. No. 4,722,858 discloses a fire-retardant sheet material manufactured from a composition of polyethylene, and from 55 to 75%, by weight, of alumina trihydrate and/or magnesium hydroxide, and optionally zinc borate and/or calcium carbonate, and at least 2% by weight of the composition being in the form of a graft copolymer with an ethylenically unsaturated carboxylic acid or anhydride. The composition has a melt index of 0.05 to 4.0 dg/min
U.S. Pat. No. 5,110,842 discloses an “electron-beam,” cured sheet-type foam comprising the following: a polypropylene type resin (A) of 100 parts by weight; a copolymer resin (B) of 5 to 40 parts by weight, which is made of ethylene and at least one selected from the group consisting of acrylic acid, ethylacrylate, maleic acid anhydride, and vinylacetate; and a copolymer resin (C) made of ethylene and an alpha-olefin of 4 to 8 carbon atoms, and having a melting point of 117° C. to 123° C., and a density of 0.890 g/cm3 to 0.910 g/cm3. This foam contains 20 to 60 percent gel content, and has an expansion ratio of 5 to 40.
European Patent Application EP 0276570A2 discloses a method for the manufacture of film from blends of polyolefins. The blend is comprised of a polyethylene, and up to 20% by weight of a polyethylene grafted with 0.5 to 2.0%, by weight, of an ethylenically unsaturated carboxylic acid or anhydride, especially maleic anhydride. The polyethylene may be a homopolymer of ethylene or a copolymer of ethylene and a C4-C10 hydrocarbon alpha-olefin, especially so-called linear low density polyethylene.
Additional polyolefin compositions are disclosed in the following: International Publication Nos. WO 2006/127873, WO 2007/127222, WO 2009/086091, WO 2010/008371, WO 2008/080111, WO 2008/103887, and WO 1997/28960; U.S. Publication Nos. 2002/0005250, 2010/0029827A1, 2011/0008567 and 2011/0120902; and U.S. Pat. Nos. 5,424,362, 5,819,392, 6,331,592, 4,868,052, 4,619,859, 4,868,052, 4,434,258, 4,403,007, 4,379,190; and CN 101318577A (Abstract), JP 3218829A (Abstract), JP 59-215828A (Abstract), JP 61-62544A (Abstract), JP2009235635A (Abstract), JP62025139A (Abstract), GB 2113696A, GB 2107325A, CA 2042893A1, CA 2331967A1, RD 280039A, and EP0688899A2.
However, the compositions of the art do not provide low growth carpet backing formulations designed to accommodate high modulus fillers, and preferably high levels of such fillers. There remains a need for new polymer compositions that have reduced growth forces, and which can be used in carpets, and in particular, in carpet backings, without causing expansion and buckling problems. This need and others have been met by the following invention.